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Reaction of sodium with water

  1. Sep 2, 2011 #1
    Does sodium reacting with water produces sodium hydroxide directly or produces sodium oxide first then hydroxide ?
     
  2. jcsd
  3. Sep 2, 2011 #2

    Borek

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    No place for oxide.

    You can think about the reaction as if HOH was an acid.
     
  4. Sep 3, 2011 #3
    So you mean that Sodium reacting with water becomes Sodium Hydroxide directly ?

    Then how is Sodium Oxide produced ?
     
  5. Sep 3, 2011 #4
    2 NaOH + 2 Na → 2 Na2O + H2
    Na2O2 + 2 Na → 2 Na2O
    2 NaNO2 + 6 Na → 4 Na2O + N2

    OR

    6 Na + 2 O2 → 2 Na2O + Na2O2
     
  6. Sep 3, 2011 #5

    Borek

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    Simplest method - roasting sodium carbonate.
     
  7. Sep 3, 2011 #6
    Thanks:)

    Does Sodium reacting with Steam produces Sodium hydroxide ? I mean the metals above Magnesium can react with steam to form metal oxide or hydroxide ?
     
  8. Sep 3, 2011 #7
    I don't think you can get sodium oxide in that way.
     
  9. Sep 3, 2011 #8

    Borek

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    Most carbonates decompose in high temperatures yielding CO2 and metal oxides, sodium carbonate is not different. It is just a matter of temperature applied. From what I remember, standard Bunsen burner should be enough to heat the carbonate high enough.
     
  10. Sep 3, 2011 #9

    chemisttree

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    Yes, that will do it. You can also roast sodium hydroxide.
     
  11. Sep 3, 2011 #10
    Answer please!
     
  12. Sep 3, 2011 #11

    Borek

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    Depends on the steam temperature. If it is low, you will get NaOH. If it is hot enough, you should get Na2, this is not much different from, the roasting.

    I have never seen roasted NaOH. It easily melts and can splash, making the experiment much more dangerous. I remember roasting carbonates.
     
  13. Sep 4, 2011 #12
    OK, that was really helpful. Thanks:)
     
  14. Sep 4, 2011 #13
    I'm confused, because here, for example, they say something different:

    http://www.practicalchemistry.org/experiments/thermal-decomposition-of-metal-carbonates,281,EX.html
    <<Students should find that sodium and potassium carbonates give no carbon dioxide or any other sign that decomposition has taken place, even after prolonged heating.>>

    http://www.chemguide.co.uk/inorganic/group1/compounds.html
    <<Heating the carbonates

    Most carbonates tend to decompose on heating to give the metal oxide and carbon dioxde.
    For example, a typical Group 2 carbonate like calcium carbonate decomposes like this:
    CaCO3 --> CaO + CO2
    In Group 1, lithium carbonate behaves in the same way - producing lithium oxide and carbon dioxide:
    Li2CO3 --> Li2O + CO2
    The rest of the Group 1 carbonates don't decompose at Bunsen temperatures, although at higher temperatures they will.>>
     
    Last edited: Sep 4, 2011
  15. Sep 4, 2011 #14

    Borek

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    That could be easy to check if someone has access to thermogravimetric curves for these carbonates. I am limited to what I can google, first one that I found

    http://www.muhlenberg.edu/depts/chemistry/webmaps/sodacarb.htm

    shows that sodium carbonate doesn't decompose up to 800 deg C, but Bunsen goes higher. Google finds also this paper: http://www.tandfonline.com/doi/abs/10.1080/00986440108912851#preview. It can't be read without paying, but google shows quote from the paper:

     
  16. Sep 4, 2011 #15
    Thanks for that link, but sincerely from that diagram it's not so obvious for me to understand that it starts decomposing at 800°C (it even acquires weight some tens of degrees before that point) and that the decomposition is in Na2O and CO2.

    And are you sure that it refers to loss of weight due to decomposition in Na2O and CO2 and not, again, to the decomposition in carbonate and water?
     
  17. Sep 4, 2011 #16

    Borek

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    Never stated that, please reread my post - I wrote that it doesn't decompose before 800, it doesn't mean it starts at 800, it means it can be expected to decompose at some higher temp.

    Sorry, no idea what you mean by "decomposition in something". Could be my English fails me.
     
  18. Sep 5, 2011 #17
    Ok. So we still don't know for sure at which temperature Na2CO3 decomposes according to:

    Na2CO3 --(heat)-> Na2O + CO2

    and if it really does it (in absence of other chemicals which reacts with at least one of the products).

    Maybe it's my english, I don't know :smile:
    I mean that sodium carbonate at room temperature is never pure because it always has some water in it. So when we say it "decomposes" it's not clear which is the reaction, it could simply be

    Na2CO3*nH2O --> Na2CO3*(n-1)H2O + H2O

    So, with "decomposes in..." I intended that "it decomposes forming..."
     
  19. Sep 5, 2011 #18

    Borek

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    Right.

    I have no doubts it does. There are no other stable substances it can decompose to, and it has to decompose at some point. Everything does, it is just a matter of temperature.

    No, it is clear. Water leaves crystals at much lower temperatures, before we get to 800 deg C (which we know is still not enough) carbonate is dry as Sahara desert.
     
  20. Sep 5, 2011 #19
    In that sense, ok. Yes, even water, e.g., decomposes into hydrogen and oxygen at temperatures high enough, but in the case of sodium carbonate how do we know that it doesn't decompose, e.g., in Na and CO2 and O2 or Na+, CO3-- and then in Na, C, O?

    Right, even because, otherwise it wouldn't be possible to make standards heating it...
     
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